This contract is for the acquisition and characterization of allosera directed against "public specificities" and DNA oligonucleotide probes directed against both "public and private specificities" of the human major histocompatibility complex (MHC). The contractor will screen sera from multiparous women and transplant or blood transfusion recipients against cell panels (This panel shall represent the various ethnic populations of the Contractor's locale in appropriate proportions) well characterized for both public and private specificities of the MHC. The contractor will also synthesize oligonucleotide probes that recognize the public specificities. The Contractor shall authenticate the purity and efficacy of these probes for the detection of specific public specificities and use these probes on the above mentioned cell panel to molecularly type the cell panel in relation to the serological definitions. Methods of screening the molecular probes should include polymerase chain reaction (PCR) technology, oligonucleotide probes and Southern hybridization procedures. The sera of interest will be acquired in larger quantities and more completely characterized by absorption/elution studies as well as standard and antiglobulin enhanced cytotoxic techniques. Cluster analysis of cell/serum reactions will be performed to more precisely define the known and newly described public specificities. At least one hundred milliliters of at least 5 new or replacement sera will be deposited each year by the contractor into the NIAID repository. The contractor shall provide the NIAID with at least 1 mg of at least two new or replacement molecular probes for the genotypic typing of public or private MHC determinants per year to be deposited into the NIAID repository.